Bi-amp question

I looked into this a while back, and for my situation it wasn't worth it. My thought was a tube amp for mids/trebble and a 200 Wpc SS amp for bass, which I had. I tried feeding both amps from the pre, so both reproducing the full bandwidth, and found no material benefit. BTW, my tube amp gas gain attenuators to match gains.

To do it right, I thought of adding a crossover between pre and amps, and had to take the speakers' passive crossover out (the bass and mids/hi). That was too much a hassle/risk and decided to leave it alone. Some people have speakers that make taking that crossover out much easier, and from a theoretical point of view actively biamping still makes sense to me...so might give it another try in the future.

Yet this configuration requires an additional crossover, an additional pair of ICs, 2 additional power cords...when you add it up I can't help but wonder how a more expensive amp driving full bandwidth would compare!

Hence, the dilema. Thanks for allowing me to share my confusion! :-)

cheers

Rodman99999: "Both amps will still remain saddled with reproducing the full signal, from your preamp."

Well...yes and no. Certainly each amp is driven by the full-band signal from the preamp, but each amp doesn't drive the same full-range signal from the preamp. This is because each amp is driving only part of the speaker's crossover. The amp driving a low-frequency end is presented with a load that increases its resistance dramatically as the frequency rises, and each amp driving a high-frequency end is presented with a load that increases its resistance dramatically as the frequency lowers.

Then if one has an amp with great-sounding bass and edgy treble, use it as a bass-end amp, and if one has an amp with great-sounding MR and treble but is a bit wimpy in the bass, use it as a upper-frequency amp.

Of course, the biggest problem with passive biamping with different amps, that of matching the different Voltage gains, still remains if one doesn't already have gain controls on the higher-gain amp.

IMO passive biamping can be rewarding, but it's not for novices unless you don't care if the tonal balance of your speaker systems ends up badly inaccurate.
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Correction: The "fine" attenuator only comes in single deck mono, so you would need two of them.

With monoblocks, that actually works better with the attenuators close to each amp, in separate enclosures.

Some "pro" amps have adjustable gain built in but it's probably just a cheap pot.

The concern over "different sounding amps" makes no sense. The drivers powered by the two amps are totally different technology, with sound characteristic differences far greater than that between two amps.

DACT has a 10k, 0 to -12 dB in 0.5 dB steps, "fine tuning" attenuator that can tame different amps. Easy enough to add series resistance if required (50K for some tube preamps). Inline with the "stronger" amp after the Y. Another pair of IC's, a small project box (Goldpoint?) and a drill, a knob, 4 female RCAs, hook-up wire and a bit of soldering.

Don't try this with pots.

Ok... I have recently purchased a set of psb synchrony ones and a NAD M3 amp(180 wpc)... if were to add another amp, say a Rotel RB-1170(130 wpc) for bi-amping... which way would make the most sense to wire them up? NAD for the Highs and Rotel for the Lows? or vice versa???
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looks like what you are wanting to try out is "dual amping" your speakers 'cuz you will continue to use the factory provided built-in x-overs.
This might or might not be beneficial, as others have already stated.
The highest probability of success (if there is any for your situation) will occur when you have 2 identical stereo amps OR 4 identical mono amps 'cuz you will not have to worry about amplifier gain, amplifier sensitivity, amplifier sonics, amplifier headroom, amplifier current delivery capability, etc. For any other situation, it's a hit or miss - the difference in the different amplifiers' capability might negate any benefit of dual-amping.
True biamping is more complex that simply dual-amping - the ultra-purist (& IMO the bold) will completely gutt or simply disconnect the entire factory provided x-over & use an external (tube/s.s) xover & the purist will disconnect the bass xover while keeping the mid/tweeter xover & still use an external xover. Usually the external xover is used between the preamp & power amp to avoid using multiple preamps.

yes, with hindsight I can see that deserves clarification. Indeed if I hadn't posted that in such a hurry I would have reworded it. I don't speak with authority on this - it's simply my experience, with my system.

I don't know how, or even if thay are designed to take advantage of biamping.......

Thanks.

03-11-12: Kr4
"I'm doing vertical passive biamp on one of my systems and it does perform better than other single amp configurations, but the speakers are unique in that they take advantage of it. "

Can you explain how the speakers are designed to take advantage of passive bi-amping?

yes, with hindsight I can see that deserves clarification. Indeed if I hadn't posted that in such a hurry I would have reworded it. I don't speak with authority on this - it's simply my experience, with my system.

I don't know how, or even if thay are designed to take advantage of biamping. They are Von Schweikert VR4GenIII's with 2 separate modules (Bass and Mid-high), each with its own crossover. When I was deciding on amps for that system I called Von Scwheikert to ask them for advice. Albert Von Schweikert answered the phone personally (on about the 3rd ring). The question I asked was "Will they perform better with vertical biamping, or with a more powerful single amp?" . . . or some wording like that. Albert went on to talk at length about the VR4GenIIIs and biamping. He first said 2 identical amps vertically biamped would out perform a single higher output amp. He further advocated running tubes on the top, SS on the bottom.

I experimented with multiple amps both biamp and non. Tubes on the top, single tube amp full range. This is how I reached my judgements. I like the vertical biamp arrangement that I have now best of those I tried. The setup I ran with tubes on the top was getting too complicated so I abandoned it. I tried single amps costing more than the 2 amps I have now; however I have not tried all of the amps, just quite a few ;-) .

I have also tried biamping on other speakers. Passive vertical biamping using Totem Mani-2s (in my other system) was fruitless (just as Totem's Support rep told me it would be). When I say 3 out of 4 tries weren't worth the effort, I mean it literally. That's how many systems I tried. For me though it was about learning/experimenting, just trying different stuff..

I have to agree with Elizabeth on this one. You really need to know what you are doing and have the right equipment. I will admit that I do a vertical biamp in my system with 2 Ayre amps and I don't mean to have a """""""""i know better than you attitude"' but if I were you, I would just list'en to music for now an'd nott worry about that now. As luck wou'ld have it, my keyboar'd broke as I am ty'ping this and now, eeven " i don''t have the equipment to deal with this' problem right' not''w.1

"I'm doing vertical passive biamp on one of my systems and it does perform better than other single amp configurations, but the speakers are unique in that they take advantage of it. "

Can you explain how the speakers are designed to take advantage of passive bi-amping?

I agree with what the others have said. Even with the exact same amps, my experience is that 3 out of 4 cases the benefits aren't worth the effort and cost of 2 amps - you're better off trading in your NAD for a better amp.

I'm doing vertical passive biamp on one of my systems and it does perform better than other single amp configurations, but the speakers are unique in that they take advantage of it. I've tried other speakers and amps with near zero resultant benefit. I also tried horizontal biamping using tubes on the top, ss on bottom - it was simply too much effort and trouble for the benefit. My speakers sounded better using the tubes full range.

I was trying to resolve the same issue with my PSB Stratus Gold speakers by trying to use a tube amp on top with a SS amp for the bass. Had difficulties with gain matching and other issues as well, but gain matching is the 1st thing that pops up, so unless you can correct for that, forget it.

Bi-amping does make sense - but only if you go with DSP/active crossover technology to replace the internal passive crossover.

to use two different sounding amps will instantly outweigh any advantage possibly gained by bi-amping.

are the PSBs so difficult to drive?

Forget it unless you have the exact same amps

The best(most successful) way to passively bi-amp, is with two identical amps. No worries about gain matching, phase/time aberrations, etc., plus-you can try it vertically and horizontally. Both amps will still remain saddled with reproducing the full signal, from your preamp. That results in much less benefit, than what is gained through actively bi-amping.

I have to agree with Elizabeth. If you don't really understand what it takes and what you are doing, you aren't going to hear a big difference. As always, just my opinion.